The present invention is generally directed to a method for preparing compounds useful in therapy. More particularly, the present invention provides a method for preparing a class of fused polycyclic alkaloids as well as novel compounds obtained thereby, pharmaceutical compositions containing them and methods of treatment using them.
Naturally occurring molecules which exhibit potentially beneficial pharmacological properties are isolable from a range of environments, such as marine, plant and microbial sources. One example of such molecules is the general class of compounds known as the Lamellarins. These polyaromatic alkaloids are isolated from marine sources and comprise a fused polyaromatic framework. Lamellarins C and D have been shown to cause inhibition of cell division in a fertilised sea urchin assay, whereas Lamellarins I, K and L all exhibit comparable and significant cytotoxicity against P388 and A549 cell lines in culture. Recently, Lamellarin N has been shown to exhibit activity in lung cancer cell lines by acting as a Type IV microtubule poison. Furthermore, these compounds have also been shown to possess cytotoxic activity on multidrug resistant cells as well as efficacy as non-toxic modulators of the multidrug resistant phenotype and, therefore, afford an attractive potential source of chemotherapeutic agents.
However, the potential clinical usefulness of the Lamellarins is severely limited by the modest quantities produced naturally as well as the difficulties involved in their isolation. Steglich and coworkers, in Angew. Chem. Int. Ed. Eng. 1997, 36, 155, have described a biomimetic sequence for the synthesis of Lamellarin G trimethyl ether, however, the process is limited in that it lacks regiochemical control and does not readily lend itself to the specific substitution patterns dictated by the natural products. There is a need, therefore, for a synthetic process which enables the production of the Lamellarins and analogues thereof.
Throughout this specification, unless the context requires otherwise, the word xe2x80x9ccomprisexe2x80x9d, and variations such as xe2x80x9ccomprisesxe2x80x9d and xe2x80x9ccomprisingxe2x80x9d, will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.
In a first aspect, the present invention contemplates a method for the preparation of a compound of general Formula (I): 
comprising the step of cyclizing an azomethine ylide of general Formula (II): 
wherein,
A is a cyclic group being an optionally substituted aryl group or an aromatic heterocyclic group; or
A is a cyclic group RA1RA2Cxe2x80x94CRA3RA4 wherein RA2 and RA3, together with the carbon atoms to which they are attached form an optionally substituted saturated or unsaturated carbocyclic or heterocyclic group and RA1 and RA4 are as defined below or together form a bond; or
A is a non-cyclic group RA1RA2Cxe2x80x94CRA3RA4 wherein RA1-RA4 are as defined below and RA2 and RA3 may optionally together form a bond;
Z is a carbon or a heteroatom;
n is selected from 0, 1, 2 or 3; and
RA1-A4, W, X and Y may be the same or different and each are selected from hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally protected hydroxy, optionally substituted amino, optionally substituted alkoxy, optionally substituted alkenoxy, optionally substituted alkynoxy, optionally substituted aryl, optionally substituted heterocyclyl, carboxy, carboxy ester, carboxamido, acyl, acyloxy, mercapto, optionally substituted alkylthio, halogen, nitro, sulfate, phosphate and cyano, or W and X, together with the nitrogen and carbon atoms to which they are attached, form a saturated or unsaturated nitrogen containing heterocyclic group which may be optionally substituted or optionally fused to a saturated or unsaturated carbocyclic group, aryl group or heterocyclic group; or pharmaceutically acceptable derivatives and salts, racemates, isomers and/or tautomers thereof.
Another aspect of the invention contemplates a compound of Formula (I) prepared by the methods as described herein.
Yet another aspect of the invention relates to novel compounds of general Formula (I) 
wherein A, Z, W, X, Y and n are as defined above, provided the compound is not Lamellarin A-N, S-X;
T, U, V or Y 20-sulfate; or D, K, L, M or N-triacetate; G-trimethyl ether; or I-acetate; as herein described.
Still yet another aspect of the present invention relates to a method of treating multidrug resistant tumours comprising the administration of an effective amount of a compound of Formula (I).
A further aspect of the invention provides compositions comprising a compound of Formula (I) together with a pharmaceutically acceptable carrier, excipient or diluent.
The azomethine ylides of general Formula (II) are obtainable from corresponding precursors by methods known to those skilled in the art, for example as described by A. Padwa et al, in Chem Rev., 1996, 96, (1), 241 and V. P. Litvinov, Russian Journal of Organic Chemistry, Vol. 31 (No. 10), 1995, pp. 1301-1340. A particularly suitable means of generating the azomethine ylide of general Formula (II) is effected by the addition of a base to a compound of Formula (III). 
wherein the counter ion Lxe2x8ax96 is a stable, weakly basic anion.
Suitable anions include those derived from the sulfonates, such as, tosylate, mesylate, triflate, bosylate, besylate, tresylate, nonaflate and nosylate and the halogens, especially chlorine and bromine and iodine. Preferably Lxe2x8ax96 is bromide or iodide.
In a preferred embodiment, the present invention provides a method for the preparation of a compound of Formula (Ia): 
comprising the step of cyclizing an azomethine ylide of general Formula (IIa): 
wherein R1-R8 and R14 are as defined for W, X and Y as described above.
Preferably, the azomethine ylide of Formula (IIa) is generated by the addition of a base to a compound of general Formula (IIIa): 
wherein R1-R8, R14, Y, Z, n and Lxe2x8ax96 are as hereinbefore described.
Suitable bases for generating the azomethine ylide of Formula (II) include those derived from alkali metals such as phenyllithium, butyllithium, KNH2 and NaNH2; metal carbonates such as potassium carbonate, lithium carbonate, sodium carbonate and cesium carbonate; as well as amines. In preference, the base used is a mono-, di- or tri-substituted amine, more preferably an alkylamine. Most preferably the base is triethylamine or diisopropylethylamine.
Cyclization of the azomethine ylide may be effected by any suitable means, such as thermal treatment or treatment with metal salts, preferably Cu(I) salts such as CuI. Preferably cyclization is effected by thermal treatment, such as by heating in optionally boiling solvent. Suitable solvents include tetrahydrofuran, chloroform and 1,2-dichloroethane.
In a further preferred aspect, the cyclization of a compound of Formula (II), is followed by oxidative treatment. Oxidative treatment may be performed by means known to and routinely carried out by those skilled in the art. Particularly suitable means include direct oxidation in air, optionally in the presence of silica gel; treatment with Fremy""s salt; treatment with quinones such as chloranil or 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), and treatment with metal catalysts such as platinum, palladium and nickel. Preferably the oxidative treatment is effected by DDQ or silica gel in air or Fremy""s salt. When Lxe2x8ax96 of compounds of Formula (III) is iodide, oxidation is promoted.
In a preferred embodiment, a compound of general Formula (I) is prepared by treating a compound of general Formula (III) with triethylamine or diisopropylamine followed by thermally induced cyclization and subsequent oxidative treatment with DDQ or silica gel in air. In a more preferred embodiment a compound of general Formula (Ia) is prepared by treating a compound of general Formula (IIIa) with triethylamine or diisopropylamine followed by thermally induced cyclization and subsequent oxidative treatment with DDQ or silica gel in air or Fremy""s salt.
When n is 1, Z is preferably selected from one of carbon, nitrogen, oxygen or sulfur. More preferably Z is nitrogen or oxygen. Most preferably, Z is oxygen. When n is 2 or 3, preferably one of Z is carbon, preferably the remaining Z are oxygen or nitrogen. Suitable examples where n is 2 or 3 include A-Oxe2x80x94CH2xe2x80x94C(O)xe2x80x94, A-CH2xe2x80x94Nxe2x80x94C(O)xe2x80x94, A-Oxe2x80x94CH2xe2x80x94Oxe2x80x94C(O)xe2x80x94 and A-CH2xe2x80x94Oxe2x80x94CH2xe2x80x94C(O)xe2x80x94.
Preferably, when W and X, together with the nitrogen and carbon atoms to which they are attached, form a saturated or unsaturated heterocyclic group, the group is optionally substituted quinolinyl, optionally substituted isoquinolinyl, optionally substituted dihydroquinolinyl, optionally substituted dihydroisoquinolinyl, optionally substituted pyridyl or dihydro or tetrahydro congeners thereof, or optionally substituted phenanthridine. Preferably, W and X together with the nitrogen and carbon atoms to which they are attached, form an optionally substituted isoquinolinyl or optionally substituted dihydroisoquinolinyl group of general Formula (i): 
wherein R1-R4 and R14 are as defined above.
Preferably R1-R4 are hydrogen, hydroxy, optionally substituted alkyl, optionally substituted alkyloxy, acyloxy, or sulfate. Most preferably they are hydrogen, hydroxy, methoxy, isopropoxy methyl, acetoxy or sulfate. Preferably R14 is hydrogen or hydroxy.
When A is an aryl group or an aromatic heterocyclic group, ring A may be an optionally-substituted benzene or naphthalene ring or an optionally substituted aromatic heterocyclic group such as pyridine, furan, pyrrole or thiophene and benzene-fused analogues thereof, for example, quinoline, indole, benzofuran and benzothiophene. Attachment of the bicyclic heterocyclic group may be via the benzene or heterocyclic ring. Preferably A is an optionally substituted benzene. Preferably the substituents are hydrogen, hydroxy, optionally substituted alkyl, optionally substituted alkyloxy, acyloxy, or sulfate. Most preferably they are hydrogen, hydroxy, methoxy, iso-propoxy, methyl, acetoxy or sulfate.
When A is a non-cyclic group RA1RA2Cxe2x80x94CRA3RA4, RA1-RA4 are preferably independently selected from hydrogen, optionally substituted alkyl, optionally protected hydroxy, optionally substituted alkoxy or acyloxy. Preferably at least one of RA1-A4 is hydrogen. More preferably at least two are hydrogen. More preferably at least three are hydrogen. Most preferably all RA1-RA4 are hydrogen. When RA2 and RA3 together form a bond so as to form the group RA1Cxe2x95x90CRA4, preferably at least one, or preferably both, of RA1 and RA4 are hydrogen.
When A is a cyclic group RA1RA2Cxe2x80x94-CRA3RA4 as defined above, preferably RA2-RA3 form a 3 to 8-membered cyclic group, preferably 5 to 6-membered. Preferably, RA2 and R3 together with the carbons to which they are attached form a cyclopentane, cyclohexane, cyclopentene, cyclohexene,cyclopentadiene, cyclohexadiene, tetrahydrofuran, dihydrofuran, pyrrolidine, pyrroline, pyran, dihydrophyran, tetrahydropyran or piperidene group. In another preferred form, RA1 and RA4 are hydrogen.
Preferably Y is an optionally substituted phenyl group of Formula (ii): 
wherein R9-R13 are as defined for R1-R8 and R14 as described above.
More preferably, R9-R13 are hydrogen, hydroxy, optionally substituted alkyl, optionally substituted alkoxy or acyloxy. Most preferably, R9-R13 hydrogen, hydroxy, methoxy, iso-propoxy, methyl, acetoxy or sulphate.
The method of the present invention is particularly suitable for the preparation of compounds 1 to 39 as depicted in Tables 1 and 2.
As used herein the term xe2x80x9calkylxe2x80x9d, denotes straight chain, branched or cyclic fully saturated hydrocarbon residues. Unless the number of carbon atoms is specified the term preferably refers to C1-20 alkyl or cycloalkyl. Examples of straight chain and branched alkyl include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, amyl, isoamyl, sec-amyl, 1,2-dimethylpropyl, 1,1-dimethyl-propyl, hexyl, 4-methylpentyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 1,1-dimethylbutyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 1,2,2,-trimethylpropyl, 1,1,2-trimethylpropyl, heptyl, 5-methoxyhexyl, 1-methylhexyl, 2,2-dimethylpentyl, 3,3-dimethylpentyl, 4,4-dimethylpentyl, 1,2-dimethylpentyl, 1,3-dimethylpentyl, 1,4-dimethyl-pentyl, 1,2,3,-trimethylbutyl, 1,1,2-trimethylbutyl, 1,1,3-trimethylbutyl, octyl, 6-methylheptyl, 1-methylheptyl, 1,1,3,3-tetramethylbutyl, nonyl, 1-, 2-, 3-, 4-, 5-, 6- or 7-methyl-octyl, 1-, 2-, 3-, 4- or 5-ethylheptyl, 1-, 2- or 3-propylhexyl, decyl, 1-, 2-, 3-, 4-, 5-, 6-, 7- and 8-methylnonyl, 1-, 2-, 3-, 4-, 5- or 6-ethyloctyl, 1-, 2-, 3- or 4-propylheptyl, undecyl, 1-, 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-methyldecyl, 1-, 2-, 3-, 4-, 5-, 6- or 7-ethylnonyl, 1-, 2-, 3-, 4- or 5-propylocytl, 1-, 2- or 3-butylheptyl, 1-pentylhexyl, dodecyl, 1-, 2-, 3-, 4-, 5-, 6-, 7-, 8-, 9- or 10-methylundecyl, 1-, 2-, 3-, 4-, 5-, 6-, 7- or 8-ethyldecyl, 1-, 2-, 3-, 4-, 5- or 6-propylnonyl, 1-, 2-, 3- or 4-butyloctyl 1-2-pentylheptyl and the like. Examples of cyclic alkyl include mono- or polycyclic alkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl and the like.
As used herein the term xe2x80x9calkenylxe2x80x9d denotes groups formed from straight chain, branched or cyclic hydrocarbon residues containing at least one carbon-carbon double bond including ethylenically mono-, di- or poly-unsaturated alkyl or cycloalkyl groups as previously defined. Unless the number of carbon atoms is specified the term preferably refers to C1-20 alkenyl. Examples of alkenyl include vinyl, allyl, 1-methylvinyl, butenyl, iso-butenyl, 3-methyl-2-butenyl, 1-pentenyl, cyclopentenyl, 1-methyl-cyclopentenyl, 1-hexenyl, 3-hexenyl, cyclohexenyl, 1-heptenyl, 3-heptenyl, 1-octenyl, cyclooctenyl, 1-nonenyl, 2-nonenyl, 3-nonenyl, 1-decenyl, 3-decenyl, 1,3-butadienyl, 1-4, pentadienyl, 1,3-cyclopentadienyl, 1,3-hexadienyl, 1,4-hexadienyl, 1,3-cyclohexadienyl, 1,4-cyclohexadienyl, 1,3-cycloheptadienyl, 1,3,5-cycloheptatrienyl and 1,3,5,7-cyclooctatetraenyl.
As used herein the term xe2x80x9calkynylxe2x80x9d denotes groups formed from straight chain, branched or cyclic hydrocarbon residues containing at least one carbon-carbon triple bond including ethynically mono-, di- or poly- unsaturated alkyl or cycloalkyl groups as previously defined. Unless the number of carbon atoms is specified the term preferably refers to C1-20 alkynyl. Examples include ethynyl, 1-propynyl, 2-propynyl, and butynyl isomers, and pentynyl isomers.
The terms xe2x80x9calkoxy, xe2x80x9calkenoxy and xe2x80x9calkynoxy respectively denote alkyl, alkenyl and alkynyl groups as hereinbefore defined when linked by oxygen.
The term xe2x80x9chalogenxe2x80x9d denotes fluorine, chlorine, bromine or iodine.
The term xe2x80x9carylxe2x80x9d denotes single, polynuclear, conjugated and fused residues of aromatic hydrocarbon ring systems. Examples of aryl include phenyl, biphenyl, terphenyl, quaterphenyl, naphthyl, tetrahydronaphthyl, anthracenyl, dihydroanthracenyl, benzanthracenyl, dibenzanthracenyl, phenanthrenyl, fluorenyl, pyrenyl, idenyl, azulenyl, chrysenyl.
The term xe2x80x9cheterocyclicxe2x80x9d denotes mono- or polycarbocyclic groups wherein at least one carbon atom is replaced by a heteroatom, preferably selected from nitrogen, sulphur and oxygen. Suitable heterocyclic groups include N-containing heterocyclic groups, such as,
unsaturated 3 to 6 membered heteromonocyclic groups containing 1 to 4 nitrogen atoms, for example, pyrrolyl, pyrrolinyl, imidazolyl, imidazolinyl, pyrazolyl, pyridyl, pyrimidinyl, pyrazinyl, pyridazinyl, triazolyl or tetrazolyl;
saturated 3 to 6-membered heteromonocyclic groups containing 1 to 4 nitrogen atoms, such as, pyrrolidinyl, imidazolidinyl, piperidyl, pyrazolidinyl or piperazinyl;
condensed saturated or unsaturated heterocyclic groups containing 1 to 5 nitrogen atoms, such as, indolyl, isoindolyl, indolinyl, isoindolinyl, indolizinyl, isoindolizinyl, benzimidazolyl, quinolyl, isoquinolyl, indazolyl, benzotriazolyl, purinyl, quinazolinyl, quinoxalinyl, phenanthradinyl, phenathrolinyl, phthalazinyl, naphthyridinyl, cinnolinyl, pteridinyl, perimidinyl or tetrazolopyridazinyl;
saturated 3 to 6-membered heteromonocyclic groups containing 1 to 3 oxygen atoms, such as tetrahydrofuranyl, tetrahydropyranyl, tetrahydrodioxinyl,
unsaturated 3 to 6-membered hetermonocyclic group containing an oxygen atom, such as, pyranyl, dioxinyl or furyl;
condensed saturated or unsaturated heterocyclic groups containing 1 to 3 oxygen atoms, such as benzofuranyl, chromenyl or xanthenyl;
unsaturated 3 to 6-membered heteromonocyclic group containing 1 to 2 sulphur atoms, such as, thienyl or dithiolyl;
unsaturated 3 to 6-membered heteromonocyclic group containing 1 to 2 oxygen atoms and 1 to 3 nitrogen atoms, such as, oxazolyl, oxazolinyl, isoxazolyl, furazanyl or oxadiazolyl;
saturated 3 to 6-membered heteromonocyclic group containing 1 to 2 oxygen atoms and 1 to 3 nitrogen atoms, such as, morpholinyl;
unsaturated condensed heterocyclic group containing 1 to 2 oxygen atoms and 1 to 3 nitrogen atoms, such as, benzoxazolyl or benzoxadiazolyl;
unsaturated 3 to 6-membered heteromonocyclic group containing 1 to 2 sulphur atoms and 1 to 3 nitrogen atoms, such as, thiazolyl, thiazolinyl or thiadiazoyl;
saturated 3 to 6-membered heteromonocyclic group containing 1 to 2 sulphur atoms and 1 to 3 nitrogen atoms, such as, thiazolidinyl; and
unsaturated condensed heterocyclic group containing 1 to 2 sulphur atoms and 1 to 3 nitrogen atoms, such as, benzothiazolyl or benzothiadiazolyl.
The term xe2x80x9cacylxe2x80x9d refers to a carboxylic acid residue wherein the OH is replaced with a residue, for example, as defined for W, X, and Y and specifically may denote carbamoyl, aliphatic acyl group or acyl group containing an aromatic ring, which is referred to as aromatic acyl or a heterocyclic ring, which is referred to as heterocyclic acyl, preferably C1-20 acyl. Examples of suitable acyl include carbamoyl; straight chain or branched alkanoyl such as formyl, acetyl, propanoyl, butanoyl, 2-methylpropanoyl, pentanoyl, 2,2-dimethylpropanoyl, hexanoyl, heptanoyl, octanoyl, nonanoyl, decanoyl, undecanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, pentadecanoyl, hexadecanoyl, heptadecanoyl, octadecanoyl, nonadecanoyl and icosanoyl; alkoxycarbonyl such as methoxycarbonyl, ethoxycarbonyl, t-butoxycarbonyl, t-pentyloxycarbonyl and heptyloxycarbonyl; cycloalkylcarbonyl such as cyclopropylcarbonyl cyclobutylcarbonyl, cyclopentylcarbonyl and cyclohexylcarbonyl; alkylsulfonyl such as methylsulfonyl and ethylsulfonyl; alkoxysulfonyl such as methoxysulfonyl and ethoxysulfonyl; aroyl such as benzoyl, toluoyl and naphthoyl; aralkanoyl such as phenylalkanoyl (e.g. phenylacetyl, phenylpropanoyl, phenylbutanoyl, phenylisobutylyl, phenylpentanoyl and phenylhexanoyl) and naphthylalkanoyl (e.g. naphthylacetyl, naphthylpropanoyl and naphthylbutanoyl]; aralkenoyl such as phenylalkenoyl (e.g. phenylpropenoyl, phenylbutenoyl, phenylmethacryloyl, phenylpentenoyl and phenylhexenoyl and naphthylalkenoyl (e.g. naphthylpropenoyl, naphthylbutenoyl and naphthylpentenoyl); aralkoxycarbonyl such as phenylalkoxycarbonyl (e.g. benzyloxycarbonyl); aryloxycarbonyl such as phenoxycarbonyl and napthyloxycarbonyl; aryloxyalkanoyl such as phenoxyacetyl and phenoxypropionyl; arylcarbamoyl such as phenylcarbamoyl; arylthiocarbamoyl such as phenylthiocarbamoyl; arylglyoxyloyl such as phenylglyoxyloyl and naphthylglyoxyloyl; arylsulfonyl such as phenylsulfonyl and napthylsulfonyl; heterocycliccarbonyl; heterocyclicalkanoyl such as thienylacetyl, thienylpropanoyl, thienylbutanoyl, thienylpentanoyl, thienylhexanoyl, thiazolylacetyl, thiadiazolylacetyl and- tetrazolylacetyl; heterocyclicalkenoyl such as heterocyclicpropenoyl, heterocyclicbutenoyl, heterocyclicpentenoyl and heterocyclichexenoyl; and heterocyclicglyoxyloyl such as thiazolylglyoxyloyl and thienylglyoxyloyl.
The term xe2x80x9cacyloxyxe2x80x9d refers to acyl, as herein before defined, when linked by oxygen.
In this specification xe2x80x9coptionally substitutedxe2x80x9d is taken to mean that a group may or may not be further substituted or fused (so as to form a condensed polycyclic group) with one or more groups selected from alkyl, alkenyl, alkynyl, aryl, halo, haloalkyl, haloalkenyl, haloalkynyl, haloaryl, hydroxy, alkoxy, alkenyloxy, aryloxy, benzyloxy, haloalkoxy, haloalkenyloxy, haloaryloxy, nitro, nitroalkyl, nitroalkenyl, nitroalkynyl, nitroaryl, nitroheterocyclyl, amino, alkylamino, dialkylamino, alkenylamino, alkynylamino, arylamino, diarylamino, benzylamino, dibenzylamino, acyl, alkenylacyl, alkynylacyl, arylacyl, acylamino, diacylamino, acyloxy, alkylsulphonyloxy, arylsulphenyloxy, heterocyclyl, heterocycloxy, heterocyclamino, haloheterocyclyl, alkylsulphenyl, arylsulphenyl, carboalkoxy, carboaryloxy mercapto, alkylthio, benzylthio, acylthio, cyano, nitro, sulfate and phosphate groups.
As used herein, the term xe2x80x9cprotecting groupxe2x80x9d, refers to an introduced functionality which temporarily renders a particular functional group inactive. The term xe2x80x9cprotected hydroxyxe2x80x9d refers to a hydroxy group which has been temporarily rendered inactive by a protecting group. Suitable protecting groups are known to those skilled in the art, for example as described in Protective Groups in Organic Synthesis (T. W. Greene and P. G. M. Wutz, Wiley Interscience, New York).
As used herein, xe2x80x9cheteroatomxe2x80x9d refers to any atom other than a carbon atom which may be a member of a cyclic organic compound. Examples of suitable heteroatoms include nitrogen, oxygen, sulfur, phosphorous, boron, silicon, arsenic, sellenium and telluruim.
As used herein, the term xe2x80x9cbasexe2x80x9d refers to any proton acceptor/electron pair donator suitable for the generation of an azomethine ylide.
The term xe2x80x9csynthonxe2x80x9d is taken to refer to a structural or chemical equivalent for a desired functional unit and which can be converted to the desired unit by known or conceivable synthetic operations
As used herein, the term xe2x80x9cleaving groupxe2x80x9d refers to a chemical group which is displaced by a nucleophile. Suitable leaving groups include those with the ability to stabilize the negative charge which it carries such as the halogens, sulfates as hereinbefore defined, protonated alcohols and ethers, pyridinium salts, iminium salts such as derived from dicyclohexylcarbodiimide (DCC) and diazonium ions.
The present invention is hereinafter described using a compound of Formula (II) prepared by the hereinafter described methods. This is done, however, with the understanding that the present invention extends to compounds of Formula (II) prepared by any other means.
Accordingly, another aspect of the invention relates to a process for the preparation of a compound of Formula (I) comprising:
a) coupling a compound of Formula (IV) with a compound of Formula (V): 
to afford the compound of Formula (VI): 
wherein PZn is a synthon for Zn.
b) unmasking Zn of compound (VI) and coupling with a compound L-CH2xe2x80x94C(O)-Lxe2x80x2, to provide compound (VII): 
wherein Lxe2x80x2 is a leaving group or a substituent convertible to a leaving group.
c) treatment of compound (VII) with an imine of Formula (VIII) 
d) generation of the azomethine ylide of general formula (II) and subsequent cyclization of the ylide:
wherein Hal is a halogen and A, L, W, X, Y, Z and n are as hereinbefore described.
In a preferred embodiment, the present invention relates to a process for the preparation of a compound of Formula (Ia) comprising:
(a) coupling a compound of Formula (IV) with a compound of Formula (Va): 
to afford the compound of Formula (VIa): 
(b) unmasking Zn of compound (VIa) and coupling with a compound L-CH2xe2x80x94C(O)-Lxe2x80x2 to provide compound (VIIa): 
(c) treatment of compound (VIIa) with a compound of Formula (VIIIa): 
(d) generation of the azomethine ylide of general Formula (IIa) and subsequent cyclization of the ylide;
wherein Hal, L, Lxe2x80x2, PZ, Y, Z, R1-R8, R14 and n are as hereinbefore defined.
Preferably Y is optionally substituted phenyl of Formula (ii). More preferably, Y is phenyl substituted with optionally substituted alkyl, optionally substituted alkoxy or acyloxy. Most preferably, Y is phenyl substituted with hydrogen, hydroxy, methoxy, methyl or acetoxy.
In a preferred aspect, P is a protecting group for Zn and unmasking Zn refers to removal of the protecting group. Removal of the protecting group P may be carried out under routine conditions known to those skilled in the art, for example as described in Protective Groups in Organic Synthesis. Preferably, P is a protecting group which is labile under hydrolysis conditions. Even more preferably, P is acetyl. In a preferred embodiment, n is 1, Z is oxygen and P is acetyl.
In another preferred aspect, wherein the terminal Z is oxygen, PZn is an aldehyde or acyl group. Unmasking of Zn comprises oxidation, such as Baeyer-Villiger oxidation, of the aldehyde or acyl to a corresponding ester followed by hydrolysis.
Other suitable synthons are known to those skilled in the art.
Preferred Lxe2x80x2 is halogen, most preferably chlorine or bromine, or OH converted to a leaving group preferably by reaction with DCC.
The coupling of compounds of general Formula (IV) with those of Formula (V) may be suitably carried out under conditions known and routinely employed by those skilled in the art, for example in the presence of catalysts such as Pd(PPh3)4, PdCl2 (PPh3)2 or Cu(I) mediated conditions, e.g., CuI, and such as those described by Sonogashira in Comprehensive Organic Synthesis, (Ed. B. M. Trost and I. Fleming, Peramon Press, New York, 1991, Vol. 3, 521).
Schemes 1 to 4 provide a schematic overview of representative methods of the invention. 
The method of the present invention encompasses the synthesis of a large group of compounds. Traditionally, drug candidates are synthesized individually, this being a time consuming and laborious process if the synthetic sequence contains even just a few steps and large numbers of compounds are to be evaluated for their biological activity. Combinatorial synthesis is an emerging technique for effectuating the generation of large libraries of molecules and has been successfully exploited in the synthesis and evaluation of small organic molecule libraries. These libraries may exist as molecules in free solution or linked to a solid phase, for example, polymer beads, pins, microtitre plates or microchips. Chemical diversity can be achieved by either parallel or split (split and mix) syntheses wherein each step has the potential to afford a multitude of compounds. Solution phase libraries may be prepared via parallel syntheses wherein different compounds are synthesised in separate reaction vessels in parallel, often in an automated fashion. Alternatively, attachment of the individual components employed in a synthetic sequence to an appropriate solid phase support allows for the further creation of chemical diversity by utilizing not only parallel synthesis but also split synthesis wherein the solid support containing the compounds prepared in the prior step can be split into a number of batches, treated with the appropriate reagent and recombined. By performing one or more of the steps a)-c), as hereinbefore described, in a parallel or split fashion, in solution phase or on solid support, the present invention is amenable to the generation of large numbers of compounds of general Formula (I).
Accordingly, another aspect of the present invention provides a means for generating compounds of Formula (I) by performing one or more of the following steps:
(a) the coupling of a compound of Formula (IV) with a compound of Formula (V),
(b) unmasking Zn of the compound of Formula (VI) and coupling with a compound L-CH2xe2x80x94C(O)-Lxe2x80x2,
(c) treatment of the compound of Formula (VII) with the imine of Formula (VIII), in a parallel or split fashion, in solution phase or on solid support.
Another aspect of the invention contemplates novel compounds of the general Formula (I): 
provided the compound is not Lamellarin A-N, S-X;
T, U, V or Y 20-sulfate; or D, K, L, M or N-triacetate;
or I-acetate as described in Tables 1 and 2 or G-trimethyl ether;.
A further aspect of the invention contemplates compounds of the general Formula (II): 
Yet another aspect of the invention contemplates a compound of general Formula (III): 
Another aspect of the invention contemplates the compounds of the general Formula (I) when prepared by the methods herein described.
Yet another aspect of the present invention contemplates a method of treatment comprising the administration of a treatment effective amount of a compound of general Formula (I), as an active ingredient, to an animal, including a human, in need thereof. Preferably the compound of general Formula (I) is prepared by the methods as hereinbefore described.
As used herein, the term xe2x80x9ceffective amountxe2x80x9d relates to an amount of compound which, when administered according to a desired dosing regimen, provides the desired therapeutic activity. Dosing may occur at intervals of minutes, hours, days, weeks, months or years or continuously over any one of these periods. Suitable dosages lie within the range of about 0.1 ng per kg of body weight to 10 g per kg of body weight per dosage. Preferably, the dosage is in the range of 1 xcexcg to 10 g per kg of body weight per dosage. More preferably, the dosage is in the range of 1 mg to 10 g per kg of body weight per dosage. Even more preferably, the dosage is in the range of 1 mg to 5 g per kg of body weight per dosage. More preferably, the dosage is in the range of 1 mg to 2 g per kg of body weight per dosage. More preferably, the dosage is in the range of 1 mg to 1 g per kg of body weight per dosage.
In a preferred embodiment, the method of treatment relates to treating multidrug resistant tumors.
In another embodiment, the method of treatment contemplates improving the antitumor chemotherapeutic effect of multidrug resistant affected drugs.
In another preferred embodiment, the method of treatment is a method for inducing apoptosis. More preferably, the method of treatment is a method of inducing apoptosis on a multidrug resistant cell.
In another embodiment, the method of treatment contemplates modulating immunological functions.
The active ingredient may be administered in a single dose or a series of doses. While it is possible for the active ingredient to be administered alone, it is preferable to present it as a composition, preferably as a pharmaceutical composition.
Yet another aspect of the invention contemplates compositions comprising a compound of general Formula (I) together with a pharmaceutically acceptable carrier, excipient or diluent. Preferably the compound of general Formula (I) is prepared by the methods as hereinbefore described.
The carrier must be pharmaceutically xe2x80x9cacceptablexe2x80x9d in the sense of being compatible with the other ingredients of the composition and not injurious to the subject. Compositions include those suitable for oral, rectal, nasal, topical (including buccal and sublingual), vaginal or parental (including subcutaneous, intramuscular, intravenous and intradermal) administration. The compositions may conveniently be presented in unit dosage form and may be prepared by any methods well known in the art of pharmacy. Such methods include the step of bringing into association the active ingredient with the carrier which constitutes one or more accessory ingredients. In general, the compositions are prepared by uniformly and intimately bringing into association the active ingredient with liquid carriers or finely divided solid carriers or both, and then if necessary shaping the product.
Compositions of the present invention suitable for oral administration may be presented as discrete units such as capsules, sachets or tablets each containing a predetermined amount of the active ingredient; as a powder or granules; as a solution or a suspension in an aqueous or non-aqueous liquid; or as an oil-in-water liquid emulsion or a water-in-oil liquid emulsion. The active ingredient may also be presented as a bolus, electuary or paste.
A tablet may be made by compression or moulding, optionally with one or more accessory ingredients. Compressed tablets may be prepared by compressing in a suitable machine the active ingredient in a free-flowing form such as a powder or granules, optionally mixed with a binder (e.g. inert diluent, preservative disintegrant (e.g. sodium starch glycolate, cross-linked polyvinyl pyrrolidone, cross-linked sodium carboxymethyl cellulose) surface-active or dispersing agent. Moulded tablets may be made by moulding in a suitable machine a mixture of the powdered compound moistened with an inert liquid diluent. The tablets may optionally be coated or scored and may be formulated so as to provide slow or controlled release of the active ingredient therein using, for example, hydroxypropylmethyl cellulose in varying proportions to provide the desired release profile. Tablets may optionally be provided with an enteric coating, to provide release in parts of the gut other than the stomach.
Compositions suitable for topical administration in the mouth include lozenges comprising the active ingredient in a flavoured base, usually sucrose and acacia or tragacanth gum; pastilles comprising the active ingredient in an inert basis such as gelatin and glycerin, or sucrose and acacia gum; and mouthwashes comprising the active ingredient in a suitable liquid carrier.
Compositions for rectal administration may be presented as a suppository with a suitable base comprising, for example, cocoa butter.
Compositions suitable for vaginal administration may be presented as pessaries, tampons, creams, gels, pastes, foams or spray formulations containing in addition to the active ingredient such carriers as are known in the art to be appropriate.
Compositions suitable for parenteral administration include aqueous and non-aqueous isotonic sterile injection solutions which may contain anti-oxidants, buffers, bactericides and solutes which render the composition isotonic with the blood of the intended recipient; and aqueous and non-aqueous sterile suspensions which may include suspending agents and thickening agents. The compositions may be presented in unit-dose or multi-dose sealed containers, for example, ampoules and vials, and may be stored in a freeze-dried (lyophilised) condition requiring only the addition of the sterile liquid carrier, for example water for injections, immediately prior to use. Extemporaneous injection solutions and suspensions may be prepared from sterile powders, granules and tablets of the kind previously described.
Preferred unit dosage compositions are those containing a daily dose or unit, daily sub-dose, as herein above described, or an appropriate fraction thereof, of the active ingredient.
It should be understood that in addition to the active ingredients particularly mentioned above, the compositions of this invention may include other agents conventional in the art having regard to the type of composition in question, for example, those suitable for oral administration may include such further agents as binders, sweeteners, thickeners, flavouring agents disintegrating agents, coating agents, preservatives, lubricants and/or time delay agents. Suitable sweeteners include sucrose, lactose, glucose, aspartame or saccharine. Suitable disintegrating agents include corn starch, methylcellulose, polyvinylpyrrolidone, xanthan gum, bentonite, alginic acid or agar. Suitable flavouring agents include peppermint oil, oil of wintergreen, cherry, orange or raspberry flavouring. Suitable coating agents include polymers or copolymers of acrylic acid and/or methacrylie acid and/or their esters, waxes, fatty alcohols, zein, shellac or gluten. Suitable preservatives include sodium benzoate, vitamin E, alpha-tocopherol, ascorbic acid, methyl paraben, propyl paraben or sodium bisulphite. Suitable lubricants include magnesium stearate, stearic acid, sodium oleate, sodium chloride or talc. Suitable time delay agents include glyceryl monostearate or glyceryl distearate.
The present invention also provides the use of a compound of general Formula (I) for the manufacture of a medicament for treatment of an animal or human in need thereof. Preferably the compound of general Formula (I) is prepared by the methods as hereinbefore described.
Another aspect of the invention contemplates an agent comprising a compound of general Formula (I) for the treatment of an animal or human in need thereof. Preferably the compound of general Formula (I) is prepared by the methods as hereinbefore described.
In a first embodiment, the agent is for treating multidrug resistant tumors.
In another embodiment the agent is for inducing apoptosis on a multi-drug resistant cell.
In yet another embodiment, the agent is for improving the anti-tumour chemotherapeutic effect of multidrug resistant affected drugs.
A further embodiment is an agent for modulating immunological functions.
Yet another aspect of the invention contemplates the use of a compound of general Formula (I) for the treatment of an animal or human in need thereof. Preferably the compound of general Formula (I) is prepared by the methods as hereinbefore described.
In a preferred embodiment, the use is in the treatment of multidrug resistant tumours.
In a further embodiment, the use is in improving the chemotherapeutic effect of multidrug resistant affected drugs.
Yet another embodiment is the use in modulating immunological functions.
In another embodiment, the invention contemplates the use of a compound of general Formula (I) for inducing apoptosis in an animal or human in need thereof. Preferably apoptosis in a multidrug resistant cell.
The following abbreviations as used in the hereinafter described embodiments of the present invention.
In one embodiment of the invention, Compound 1 was prepared by Sonogashira cross-coupling of phenylacetylene and o-iodophenylacetate to give, after hydrolysis of the initial coupling product, o-hydroxytolan. This last compound was reacted with bromoacetylbromide under standard conditions to deliver the ester which was then treated with isoquinoline to give the isoquinoline salt which was immediately treated with triethylamine (so as to generate the associated azomethine ylide) in refluxing THF and the mixture of dihydropyrrole-type cycloaddition products thereby obtained were subjected to oxidation with either 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) or silica gel in air. In his manner, the target Compound 1 was obtained and its structure established by single-crystal X-ray analysis.
In another embodiment, subjection of a more highly oxygenated tolan-ester to reaction with 6,7-dimethoxy-3,4-dihydroisoquinoline under the same conditions as employed in the formation of Compound 1 provided the 8,9-dihydro-congener Compound 34. Deprotection of Compound 34 with BCl3 or AlCl3 then gave Compound 35.
The present invention is now described with reference to the following non-limiting Examples.